Portable forced-air heater



Feb. 10, 1970 J. J. STUPAK, JR., ET A 9 PORTABLE FORCED-AIR HEATER FiledOct. 6, 19s? 3 Sheets-Sheet} IIIIIIIIIIII INVENTOR. JOS/W J 670341;gar/A50 &. Jo/vas M @g ATTOZ/WEVS Feb. 10, 1970 J. J. STUPAK, JR., ET ALPORTABLE FORCED-AIR HEATER 3 Sheets-Sheet 5 Filed Oct. 6, 1967 V, w muwm M U m H 2 W United States Patent 3,494,599 PORTABLE FORCED-AIR HEATERJoseph J. Stupak, Jr., and Howard B. Jones, Upland, Calif., assignors toScheu Products Company, Upland, Calif., a limited partnership ofCalifornia Filed Oct. 6, 1967, Ser. No. 673,469 Int. Cl. F231 9/04;F2311 /24 U.S. Cl. 263-19 8 Claims ABSTRACT OF THE DISCLOSURE Thisinvention relates to heaters and more particularly to a relativelycompact and portable forced-air heater for providing a high-heat output.

Various types of heaters and forced-air heaters have been devised in thepast. Typical heaters having a highheat output have been relativelylarge and bulky and sometimes have lacked suitable safety features.

Accordingly, it is a principal object of this invention to provide a newportable forced-air heater.

It is an additional object of this invention to provide a compact andlightweight forced-air heater which is of relatively simple constructionand which may be readily disassembled for service.

Another object of this invention is to provide a forcedair heater whichis safe and reliable in operation.

A further object of this invention is to provide an improved burnerassembly and control for a forced-air heater.

An additional object of this invention is to provide an improvedforced-air heater which uses vapor or liquid gas.

These and other objects and features of the present invention willbecome better understood through a consideration of the followingdescription taken in conjunction with the drawings in which:

FIGURE 1 is a side view of a portable heater according to the presentinvention;

FIGURE 2 is an inlet end view of the heater of FIG- URE 1;

FIGURE 3 is a circuit diagram of a control system for the heater;

FIGURE 4 is 'a side sectional view of the control assembly for theheater;

FIGURE 5 is a top sectional view of the control assembly of FIGURE 4;

FIGURE 6 is a cross-sectional view of a portion of the heaterillustrating the placement of the burner assembly and tube linerthereof;

FIGURE 7 is a view of the burner assembly taken along a line 77 ofFIGURE 6;

FIGURE 8 is a view of the burner assembly taken along a line 88 ofFIGURE 6;

FIGURE 9 is a cross sectional view of a portion of the burner assemblytaken along a line 99 of FIGURE 7; and

FIGURE 10 is a simplified illustration of the placement of the tip-overswitches.

Among the principal features of the present invention are theconstruction of the present heater and the burner assembly which enablea relatively lightweight and compact heater of high-output capabilitiesto be provided. The

3,494,599 Patented Feb. 10, 1970 entire heater is enclosed, and severalsafety features are provided to insure that the heater is safe inoperation. The safety features include a time delay ignition circuit toturn off the gas supply it ignition does not occur within apredetermined time, as Well as overheat and tipover controls. The heateris constructed of separable components so that the same may bedisassembled relatively simply. Additionally, a liner used within theshell of the heater allows the exterior of the shell to be relativelycool even though a typical output temperature of the heater is 3400Fahrenheit. The heater may be operated on liquid or vapor gas. A heaterconstructed in accordance with the teachings of the present inventionmay provide an adjustable burning rate of, for example, 100,000 to350,000 B.t.u.s per hour and heat, for example, an area ten feet acrossat a distance of thirty to forty feet. Heaters of this nature are usedfor space or localized drying, crop or animal drying, deth'awingequipment, and so forth.

Turning now to the drawings, the forced-air heater of the presentinvention includes an outer metal tubular shell 10 within which ismounted a blower including a fan motor 11 and blade 12. Also mountedwithin the shell 10 is a burner assembly 13 and a liner 14. The shell 10is mounted on a control assembly or box 15 which houses the controlcomponents for the motor and burner. An inlet grill 16 and carryinghandle 17 are provided. A typical heater may be approximately 20 inchestall and 30 inches long, with the diameter of the shell 10 beingapproximately 13 inches. The construction of the burner assembly 13 andthe gas and air paths of the burner assembly enable the heater to beshorter for a given B.t.u. output and good combustion than typicalheaters of this nature.

The motor 11 is mounted within the shell 10 on a motor mounting plate20, and the burner assembly 13 is mounted within the shell 10 onbrackets 21 and secured to the top of the shell by a bolt 22. The liner14 is mounted within the downstream end of the shell 10 by means ofspacers 23 through 26 as best seen in FIGURE 7. The spacers may be spotwelded or bolted between the shell and liner. The shell 10 is bolted tothe top of the control box assembly 15. A control panel 30 and an accesspanel 31 are provided as covers for the control box assembly 15.

The burner assembly 13 includes a burner venturi mixer and burner 33 asbest seen in FIGURES 6 and 7, and the same may be constructed of castaluminum. The burner assembly also includes a flame spreader backplate34, which may be formed of stainless steel, and a front plate 35. The.backplate 34 is mounted on a step 36 of the burner venturi 33, and thefront plate 35 is spaced from the venturi by means of a plurality ofspacers 37. The plates 33 and 34 and spacers 37 are secured to theburner venturi 33 by means of a plurality of bolts and nuts. A gasnozzle assembly 40, which will be explained in more detail subsequently,is secured to the bottom of the shell 10 as best seen in FIGURES 4 and 6by means of a support bracket 41 and supplies gas to the throat 42 ofthe burner venturi 33. The throat 42 is restricted at 43, and a typicaldiameter at the restriction is one inch. The venturi includes a chamberin the form of an elbow which flares slightly upstream of the throatsuch that the outlet 44 thereof has a slightly greater diameter, such asone and one-eighth inch. An igniter, such as a spark plug 45 is providedto ignite the gas and air mixture emanating from the outlet of theburner venturi. The primary air for combustion is derived from air blownby the blower which enters the throat 42 along with gas from the nozzleassembly 40.

The flame spreader backplate 34 is cupshaped and has a plurality ofholes therein through which air from the blower may pass and mix withthe air/ gas mixture from he burner venturi. This is secondary air tocomplete comustion. The flame normally commences between the ront andbackplates a fraction of an inch from the peiphery of the front plate,and this is a function of gas rressure and velocity. The backplate 34has, for example, hree rows of sixteen holes each as shown in FIGURESand 8. The inner row of holes may be on a radius of 2 /2 nches, the nextrow of holes on a radius of 3% inches, vnd the outer row of holes on aradius of 3 inches. Each of the holes typically may be inch in diameter,nd adjacent holes are spaced apart 11% degrees. It will he apparent thatthe air supply for combustion is forced vith the principal mixingoccurring in the burner venturi :hamber. The burner arrangementillustrated enables the hell 10 to be shorter than usual while stillproviding a nigh B.t.u. output and good combustion. The liner 14 acts .sa reflector to maintain the shell 10 cool. Inasmuch as here is anannular forced air space about the liner 14, teat absorbed by the lineris removed by the flowing air tream.

Turning now to the control box assembly 15, the same iouses the controlcomponents for the present forced-air leater. A gas inlet 50 is coupledwith a solenoid valve 51 vhich is coupled through a nipple 52 to apressure regllator 53. The inlet 50 and solenoid valve 51 may be se-:ured to the control panel 30. The pressure regulator 53 ncludes acontrol knob 54 for setting the inlet pressure the heater. The outlet ofthe pressure regulator 53 is :oupled through a T connector 55 andthrough a line 56 o a pressure gauge 57. The outlet also is coupledthrough L line 58, a connector 59 and a connection line 60 to the 102216assembly 40. The line 60 is coupled by means of L nut 62 and an adapter63, of the nozzle assembly 40 to he nozzle 64. The nozzle 64 is securedto the bracket 41 )y a nut 65. An aperture 66 is provided in the bottomof he shell 10 to allow the gas from the nozzle 64 to flow o the throat42 of the burner venturi 33. If it is desired 0 use liquid gas, a liquidvaporizer loop (not shown) is wed in place of the connection line 60.The vaporized oop may be, for example, approximately a two-foot ength oftubing which extends from the connector 59 to he nozzle assembly 40, butwhich extends up into the .hell 10 adjacent the burner assembly 13 toenable vaporzation of the liquid gas. For moderate flow rates and nornaltemperatures, vapor gas is used in conjunction with a gaseous withdrawaltank. In very cold weather or when a ery high flow rate is desired toprovide a high-heat outiut, the vaporizer loop is used along with aliquid withlrawal tank. If desired, several vapor tanks may be gangedtogether to provide sufiicient gas to operate with he connection line 60where a high-heat output is reruired.

The control box assembly 15 also houses electrical components forcontrolling the heater. These components are llustrated in FIGURES 4 and5, and a circuit diagram :hereof appears in FIGURE 3. A thermostat 70 isnounted on the control panel 30 and includesa control rnob 71 and dialplate 72. A red Warning light 73 and a Iellow ignition light 74 also aremounted on the control panel 30. An igniter transformer 76, ignitercontrol 77 and terminal strip 78 also are mounted in the control box asbest seen in FIGURES 4 and 5. A flame sensor 80 s mounted within thecontrol box 15, and this sensor in- :ludes a probe 81 extending into theshell adjacent the :op of the backplate 34 to sense the existence of aflame from the burner assembly. A tip-over switch assembly also ismounted within the control box assembly and ncludes a pair of mercuryswitches 84 and 85 mounted an a forty-five degree angle with respect toa vertical plane :xtending through the center of the heater as best seeni FIGURES 5 and 10. These switches are mounted upon a Jracket 86. Thetip-over switch assembly serves to shut air the gas supply and ignitingsystem if the heater is ;ipped to the side (as seen in FIGURES 2 and 10)approxmately forty-five degrees or more or tipped up on end (as seen inFIGURE 1 and FIGURE 10) approximately ninety degrees. A high temperaturelimit switch 88 is affixed to the upstream end of the shell 10 near theburner assembly 13. This switch serves to shut down the heater if thesame overheats or if the blower fails. The wiring between the variouselectrical components is not illustrated in FIGURES 4 and 5 so as not tounduly clutter these figures. Four feet-only feet 90, 91 and 92 beingseen in the drawings-are secured to the bottom of the control boxassembly 15.

Turning now to consideration of the electrical control system andoperation of the heater, a circuit diagram of the control system isillustrated in FIGURE 3. An input two conductor A.C. line 95 suppliespower to the control circuit, and one conductor 96 is coupledthrough afuse 97 to the thermostat 70, and the other conductor 98 is a commonline. The red lamp 73 is connected across the input supply, and theblower motor 11 is coupled between the output of the thermostat 70 andthe conductor 98. The thermostat 70 is coupled through the tip-overmercury switches 84 and 85 to the ignitor control 77. The ignitorcontrol 77 includes a resistive heater 99 coupled in series with a relaycoil 100 and the flame detector switch 80. The heater 99 operates asafety switch 101 after a predetermined delay, such as forty-fiveseconds. The relay coil 100 operates a switch 102 which is coupled witha solenoid 103 of the solenoid gas valve 51. The solenoid 103 in turn isconnected through the high limit switch 88 back to the conductor 98. Aresistance 104 is coupled across the switch 102. The yellow lamp 74 andthe primary 104 of the ignitor transformer 76 are coupled across theoutput of the ignition control 77. The secondary 105 of the transformer76 is coupled with the spark plug 45. The resistance 104 is a holdingresistance and has a value high enough so as not to allow operation ofthe solenoid valve 51 unless the switch 102 is closed. However, once theswitch 102 closes to energize the solenoid 103, this switch may open andsufiicient current flows through the resistance 104 to hold the solenoidvalve 51 open. If the switch opens, either switch 84 or opens, or thesupply voltage drops too low the solenoid valve 51 closes and cannotreopen until the switch 102 is caused to reclose.

With power supplied to the input line and gas sup plied to the gas inlet50, the red lamp is on serving as a warning that the heater may operateautomatically at any time. The knob 71 of the thermostat 70 is rotatedto close the contacts thereof which cause the blower motor 11 to turnon. If one of the safety devices, e.g., the tip-over switches, has notbeen activated, the ignition cycle begins. The yellow lamp 74 is onduring the ignition cycle. Current is supplied through the tip-overswitches 84 and 85 and the safety switch 101 as well as the flamedetector switch 80 to the ignition transformer 76 thereby activating thespark plug 45. Current also is supplied through the resistance heater 99to energize the relay coil which in turn closes the switch 102 toenergize the solenoid 103 and open the gas valve 51. Gas is thensupplied to the nozzle assembly 40, and the spark plug 45 causesignition at the burner assembly. After the time delay of the heater 99and safety switch 101, the ignition control 77 turns off. If the burnerflame is too small or if the burner does not ignite, the flame sensorswitch 80 does not open. If this occurs, the gas valve will be closed atthe end of the delay provided by the ignition control. Thus, ifeverything is operating properly the spark plug 45 ignites the gas andwhen the flame is sensed by the flame detector the switch 80 thereofturns off the ignition control 77. If ignition is not accomplishedwithin the delay period, the switch 101 opens thereby deenergizing thesolenoid 103 and the ignition transformer 76. If this occurs, the heatermay be manually turned off several minutes thereby allowing the switch101 to again close and the foregoing cycle be repeated. Also, the heatershould be checked and any malfunction, i.e., tipped over, should becorrected.

If the heater is tipped to either side approximately forty-five degrees,or tipped on end approximately ninety degrees, one of the mercuryswitches 84 or 85 will open and turn oif power to the ignitor control 77and solenoid 103 of the valve 51. The blower motor 11 will continue torun in order to cool the heatenas quickly as possible. 'In the event theheater over heats, the high limit switch 88 senses this condition andturns ofl? power to the solenoid 103. After this switch 88 and the flamedetector switch 80 close, the ignition cycle will be repeated. Suchexcessive temperature will occur if the inlet air or exhaust is blockedto the extent that burning is hampered thereby producing carbonmonoxide, or if the blower motor 11 or the pressure regulator 53supplies excessive gas. The pressure rating of the solenoid valve may beselected at a maximum value, such as 135 p.s.i., at which it will notopen to prevent rupture of the pressure regulator. -Excessive inletpressure may occur if the heater is misconnected in some manner.Usually, a regulator preset at a given pressure, such as 40 p.s.i., atthe supply tank (not shown) will limit the pressure to the heater.

if there is a power failure or the voltage drops too low, the solenoidvalve 103 will cause the gas to be turned ofl. If the gas supply fails,no dangerous situation is present but the heater will attempt toreignite. If, after the time delay of the ignition control no flame isestablished, the heater will turn off and will not restart until turnedoff manually for several minutes to allow the switch 101 to close. Thesame occurs if the gas pressure becomes too low. If desired, a switchmay be provided to turn off the entire heater if the power supplyvoltage drops below a predetermined level.

In operating the heater, a vapor or liquid gas supply tank (not shown)is coupled with the inlet 50. With the gas supply tank turned off andthe thermostat 70 turned off, the powerline 95 is connected with thepower supply. The valve on the tank is opened and the thermostat knob 71is rotated to a full on position. The heater automatically ignites, andthen the pressure regulator control knob 54 may be adjusted to obtainthe desired B.t.u. output. The thermostat is then set to the desiredtemperature, and the heater turns on and off automatically as thetemperature varies. The heater is turned off by closing the valve to thegas tank, and then allowing the heater to continue to operate until allremaining fuel in the lines has been burned. The thermostat is thenturned off. In the event the heater automatically turns off because ofan emergency condition, e.g., has been tipped over, the thermostat isturned off and the cause of the automatic shutoff is corrected. Afterseveral minutes, the heater may be restarted according to the foregoingprocedure.

The present embodiments of this invention are to be considered in allrespects as illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and range ofequivalency of the claims therefore are intended to be embraced therein.

What is claimed is:

1. A burner assembly for a forced-air heater having a shell throughwhich air is forced, said assembly comprisventuri mixer and burner meanshaving an inlet end in the form of a substantially conical throat withinand spaced from said shell for receiving gas and forced arr,

said mixer and burner means having a chamber therethrough for receivingforced air and gas and for mixing and supplying the same to the outletof said chamber, said chamber outlet being slightly flared outwardlyupstream of said throat,

first spreader plate means being mounted on said mixer and burner meansand extending generally laterally from said outlet, said first platemeans having apertures therein through which additional forced air mayflow and mix with said air and mas mixture to complete combustionthereof, and

second plate means mounted on said mixer and burner means adjacent tobut spaced from and laterally across the outlet of said chamber fordeflecting the mixture flowing from said chamber to flow generallylaterally along said first plate.

2. A burner assembly as in claim 1 wherein said first plate means iscup-shaped having apertures in the base thereof, and said second platemeans is a solid circular plate mounted within the cup of said firstplate, and

ignition means mounted on said mixer and burner means adjacent theoutlet of said chamber for igniting the mixture flowing therefrom. 3. Acontrol system for a forced-air heater employing a blower motor forforcing air past a burner, and a solenoid operated gas valve forsupplying gas to said burner, comprising input power supply lines, oneof said power supply lines being coupled through a thermostat to anoutput terminal thereof which in turn is coupled with said blower motor,and the other of said powerlines being a common line coupled to saidmotor,

tip-over switch means for causing said solenoid valve to be de-energizedupon the occurrence of a predeter mined event, flame detector means fordetecting a predetermined flame temperature in the vicinity of saidburner,

ignition control means, said ignition control means including a pair ofinput terminals, a first of which is coupled through said tip-overswitch means with the output terminal of said thermostat, and the secondof which is coupled through said flame detector switch means to saidcommon power line, said ignition control means including first andsecond output terminals, said solenoid valve being coupled in serieswith limit switch means between said first output terminal of saidignition control means and said common power supply line, and

igniting means for supplying igniting energy to said gas, said ignitingmeans being coupled between the second output terminal of said ignitioncontrol means and to the second input terminal of said ignition controlmeans, said ignition control means including delay means for supplyingigniting energy to said gas and for terminating said igniting energy ifignition of said gas does not occur within a predetermined time period.

4. A forced-air heater comprising shell means having blower meansmounted therein for forcing air through said shell means, said shellmeans having a longitudinal axis,

burner means mounted within said shell means, said burner means servingto receive an air-gas mixture which is burned,

control means coupled with said burner means for con trolling theoperation thereof, said control means including a gas valve forsupplying gas to said burner means and including igniting means forigniting the gas and air mixture from said burner means, and tip-overswitch means coupled to said control means for controlling the operationof said gas valve and terminating gas supply to said burner means in theevent said heater is rotated about said longitudinal axis of said shellmeans a predetermined amount or said longitudinal axis of said shellmeans is tipped a predetermined amount from horizontal, said tipoverswitch means comprising a pair of electrical switches each having amovable electrical conductor therein responsive to movement of saidswitches, said switches being coupled with said shell means and beingmounted at an angle with respect to each other. 5. A heater as in claim4 wherein said switches are mounted each approximately at a forty-fivedegree angle with respect to a vertical plane extending through saidlongitudinal axis of said shell means.

6. A portable forced-air heater comprising shell means having blowermeans mounted therein for forcing air through said shell means,

burner means mounted within said shell means, said burner means servingto receve an air-gas mixture which is burned,

a solenoid gas valve coupled with said burner means for supplying gas tosaid burner means,

igniting means for'igniting the gas-air mixture from said burner means,i

ignitioncontrolmeans coupled with said solenoid gas valve and saidigniting means for controlling the operation thereof, said 1 ignitioncontrol means .including an electricaldelay circuit for supplying igniting energy to said ignition means and for terminating said ignitingenergy if'ignition of said air-gas mixture does not occur within apredetermined time period; said electrical delay circuit including asafety switch coupled between a source of electrical energy and saidignition means, and including a delay device coupled with said safetyswitch for opening said switch after a predetermined period of time;

said ignition means including a relay operated switch coupled in serieswith said solenoid gas valve and including a relay winding for operatingsaid relay operated switch coupled in series with said delay device;

a flame sensor switch coupled in series with said relay winding anddelay device, said relay operated switch and solenoid gas valve beingcoupled in parallel with the series connection of said flame sensorswitch, relay 'winding and delay device; and

tip-overiswitch means coupled'in series between said safety switchandsaid source of electrical energy, said tip-over switch means comprisinga pair of electrical switches each having a movable electrical conductortherein responsive to movement of said switches, said switches beingcoupled with said shell means and being mounted at an angle with respectto each other.

7. A heater as in claim 6 wherein said burner means has an inlet spacedfrom said shell means for receiving air from said blower means and forreceiving gas, said burner means including a chamber there-through fromsaid inlet to an outlet for mixing gas from a gas nozzle spaced from andcommunicating with the inlet of said chamber and air from said blowermeans and supplying the mixture to said outlet, first and secondspreader plate means being mounted on'said burner means, oneof saidplate means having a plurality of apertures therein through whichadditional air from said blower shell means having blower means mountedtherein for forcing air through said shell means, t burner means mountedwithin said shell means, said burner means serving to receive an air-gasmixture which is burned, v a solenoid gas valve coupled with said burnermeans for supplying gas to said burner means, 7 1 igniting means forigniting the gas-air mixture from said burner means, 7 a flame sensorswitch mounted near said burner means for. sensing the heat therefrom,said sensor switch being coupled to control'said igniting means and turnoff the same whena predetermined flame emanates from said burner means,

ignition control means coupled with said solenoid gas valve and saidigniting means for turning on said valve and supplying electrical energyto said igniting means for a predetermined period of time, said ignitioncontrol means including a safety switch coupled with said igniting meansfor turning off said igniting means after a predetermined period of timein the event the igniting means is not turned off by said flame sensorswitch; and

tip-over switch means coupled to said ignition control means toterminate the supply of electricalenergy thereto in the event saidheateris tipped a predetermined amount, said tip-over switch meanscomprising a pair of electrical switches each having a movableelectrical conductor therein responsive to movement of said switches,said switches being coupled with said shell means and being mounted atan angle 1 with respect to a vertical plane extending through thelongitudinal axis of said shell means.

References Cited UNITED STATES PATENTS 3,050,111 8/1962 Hubbard et a1431-243 3,338,287 8/1967 Clark 43171 3,114,538 12/1963 Kennedy.

3,126,198 3/1964 Wise. 3,210,059 10/ 1965 Nesbitt et al.

3,306,335 2/1967 Myers.

3,314,411 4/ 1967 Power 12685 3,319,947 5/1967 Truesdell.

EDWARD G. FAVORS, Primary Examiner US. Cl. X.R.

